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10 Years at GSC (Genomic Sciences Center)

Determination of the three-dimensional structure of a protein, which plays a central role in DNA recombination



The Protein Research Group determined the three-dimensional structure of the Dmc1 protein, which plays a central role in DNA recombination. This process plays a key role in introducing variation in the genomic information of the offspring. The genomic DNA inside germ cells is packaged into highly ordered structure called the chromosome, and DNA recombination takes place on these chromosomes, in which parts of the DNA originating from the father and from the mother is swapped.
  The members utilized recombinant technology to produce the human Dmc1 protein in bacterial cells and purified the protein to homogeneity. The Dmc1 protein was then crystallized, and the crystal structure of Dmc1 was successfully determined by using the data collected at the SPring-8 synchrotron radiation facility.
  The Dmc1 protein forms a double ring structure, in which the two rings, each having a diameter of 13 nm (nm=10-9 m), are stacked. The Dmc1 double-ring structure contains two open-ended passages: one at the center of the ring and the other between the stacked rings. Based on biochemical studies, the central channel was shown to bind double-stranded DNA, while the passage at the side of the ring that leads to the central channel was shown to bind single-stranded DNA. The present findings indicate that the double ring structure is the functional form of Dmc1, and provides important insights to the mechanism of DNA recombination reaction.
  This work was published in the May 7th issue of the US journal, Molecular Cell.